There is a growing demand for extracting a print frame image (still image) from a movie formed from a plurality of frame images and using it as a still image. However, a movie recorded with a high-speed shutter is jerky. Even when one image (frame image) is extracted from a movie recorded with a low-speed shutter, the frame image suffers a motion blur. It is difficult to remove a motion blur by filtering.
According to Coded Exposure Photography: Motion Deblurring using Fluttered Shutter by Ramesh Raskar, ACM SIGGRAPH 2006, the shutter is opened/closed in accordance with a predetermined pattern (intermittent pattern). A motion blur in intermittently captured images can be removed using the intermittent pattern and motion information (direction and speed of a motion).
The intermittent pattern will be supplementally explained. The photographing time of one image by a video camera is 1/60 sec. In intermittent photographing using the intermittent pattern, the shutter is not kept open for 1/60 sec. Instead, the time of 1/60 sec is divided, for example, into 1,000, and photographing is done by opening and closing the shutter for every divided short time. In this case, defining a state in which the shutter is open as 1 and a state in which it is closed as 0, the intermittent pattern can be expressed by a binary number of 1,000 digits.
Generally when an object in motion is photographed not intermittently but at a low shutter speed at which a motion blur occurs, an image with a motion blur region containing various spatial frequencies is captured. Various spatial frequencies contained in the motion blur region of the image make it difficult to uniquely determine a PSF (Point Spread Function) expressing a blur pattern. It is therefore difficult to remove a motion blur using the inverse filter of the PSF. However, intermittent image photographing can limit specific spatial frequencies in the motion blur region of an image. Coded Exposure Photography: Motion Deblurring using Fluttered Shutter by Ramesh Raskar, ACM SIGGRAPH 2006 describes a method of generating an intermittent pattern which limits spatial frequencies to uniquely determine the PSF. This reference also explains a technique of removing a motion blur using the inverse filter of an estimated PSF.
However, specific spatial frequencies are limited in the motion blur region of intermittently photographing images. This results in multiple outlines of a moving object, which is visually unnatural and is not suited to view intact.